Multidimensionality of schizotypy under review

Abstract

The purpose of this article was to review dimensional studies of schizotypy in the last decade; particularly, its nature and structure, for a better understanding and definition of this construct. Data from those studies indicate that schizotypy is a multidimensional construct consisting in three or four dimensions. A Positive factor (Unusual experiences) and a Negative factor (Anhedonia) were widely confirmed, but a third or even a fourth dimension (Disorganization, Impulsive non-comformity, Paranoia or Social Anxiety) were also found. Dimensions of schizotypy vary according to gender and age, showing men higher scores in the Negative dimension than women, while women score higher in the Positive dimension and in the Social Anxiety factor than men; however, a precise comparison is hindered by the instruments, the samples, and the statistical model used. The Schizotypal Personality Questionnaire is most studied instrument, as it shows good consistency in a tri-factorial solution. Factorial analyses of schizotypy were done in very different cultures. Future research should bear several aspects in mind: methodological shortcomings, a combined use of different measures of schizotypy, the study of this construct in different cultures, and the relationship of schizotypy with other variables.

Full text

ne of the most important challenges for
psychopathology today is the study of the features
and characteristics that make people vulnerable to
the appearance of psychological disorders. Thus, current
research efforts are aimed at detection of and early
intervention in people with a propensity for developing
psychological problems. In this regard, studies on early
intervention in schizophrenia are quite well-developed by
comparison with those on other disorders. The literature
indicates that early intervention in schizophrenia is a
good predictor of obtaining better results in treatment
(McGlashan & Johannessen, 1996), a finding that has led
to the development of a wide variety of programmes
throughout the world (Vallina, Lemos Giráldez, &
Fernández, 2006).
Schizotypy has been since its origins closely related to
psychosis. The schizotypy concept, also referred to by the
term psychosis proneness (Chapman, Edell, & Chapman,
1980), can be seen as a normal personality dimension or
as an indicator of predisposition to psychoses (Claridge,
1997; Cyhlarova & Claridge, 2005). Diverse studies
indicate that psychotic experiences are present in the
normal population, suggesting the existence of a
MULTIDIMENSIONALITY OF SCHIZOTYPY
UNDER REVIEW
Eduardo Fonseca-Pedrero, José Muñiz, Serafín Lemos-Giráldez, Eduardo García-Cueto,
Ángela Campillo-Álvarez and Úrsula Villazón García
University of Oviedo
The purpose of this article was to review dimensional studies of schizotypy in the last decade, particularly on its nature and
structure, with a view to a better understanding and definition of this construct. Data from these studies indicate that schizotypy
is a multidimensional construct consisting of three or four dimensions. A Positive factor (Unusual experiences) and a Negative
factor (Anhedonia) were widely confirmed, but a third or even a fourth dimension (Disorganization, Impulsive Nonconformity,
Paranoia or Social Anxiety) were also found. Dimensions of schizotypy vary according to gender and age, men presenting
higher scores in the Negative dimension than women, while women score higher than men in the Positive dimension and in the
Social Anxiety factor; however, a precise comparison is hindered by the instruments, the samples, and the statistical model used.
The Schizotypal Personality Questionnaire is the most widely studied instrument, as it shows good consistency in a tri-factorial
solution. Factorial analyses of schizotypy were carried out in widely differing cultures. Future research should bear several
aspects in mind, notably: methodological shortcomings, the combined use of different measures of schizotypy, the study of this
construct in different cultures, and the relationship of schizotypy to other variables.
Key words: Review, Schizotypy, Psychosis proneness, schizotypal traits, Factor analysis
El objetivo del presente trabajo consistió en llevar a cabo una revisión de las dimensiones de la esquizotipia en la última
década. La finalidad fue estudiar la naturaleza y estructura de la esquizotipia de cara a una mejor comprensión y delimitación
del constructo. Los datos indican que la esquizotipia es un constructo multidimensional que se puede concretar en tres o cuatro
dimensiones. El factor Positivo (Experiencias Inusuales) y el factor Negativo (anhedonia) han sido ampliamente replicados. El
tercer y/o cuarto se concreta en una dimensión de Desorganización, de No Conformidad Impulsiva, de Paranoia o Ansiedad
Social. Las dimensiones de la esquizotipia varían en función del sexo y la edad. Los varones tienden a puntuar más elevado
que las mujeres en la dimensión negativa mientras que las mujeres lo hacen en la dimensión positiva y en el factor Ansiedad
Social. La comparación estricta entre los estudios factoriales se encuentra dificultada por el tipo de instrumento, la muestra
empleada y el modelo estadístico utilizado. El Schizotypal Personality Questionnaire es el cuestionario más investigado,
mostrando gran consistencia en su solución trifactorial. Los estudios factoriales de la esquizotipia se han realizado en una
amplia variedad de culturas. Las futuras investigaciones deberán tener presente las limitaciones metodológicas, la aplicación
de diferentes medidas de esquizotipia de forma conjunta, el estudio del constructo a través de las diferentes culturas y la
relación de la esquizotipia con otras variables.
Palabras clave: Revisión, Esquizotipia, Propensión a la psicosis, Rasgos de la esquizotipia, Análisis factorial
Correspondence: Eduardo Fonseca-Pedrero. Facultad de Psicolo-
gía. Plaza Feijoo, s/n. Oviedo 33003. España.
E-mail: uo67776@uniovi.es
Regular articles
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Papeles del Psicólogo, 2007. Vol. 28(2), pp. 117-126
http://www.cop.es/papeles
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MULTIDIMENSIONALITY OF SCHIZOTYPY
dimensional continuum (Johns & van Os, 2001) between
the normal population and such experiences (Verdoux &
Van Os, 2002). Schizotypy is within the framework of this
model (Claridge, 1997), also extending from non-
pathological personality (health) to psychosis (illness).
Variations along this continuum describe different
degrees of predisposition to psychotic disorders. Such
vulnerability or predisposition to schizophrenia is
expressed, then, along a psychopathological continuum.
The relevance of research on schizotypal features rests
on three basic points. First of all, it helps to improve
understanding of the mechanisms underlying
schizophrenia, exploring the links between the two
entities. Secondly, it permits the study of subjects free of
psychotic illness, without the side effects of medication
and iatrogeny (Heron, Jones, Williams, Owen, Craddock,
& Jones, 2003; Martinena Palacio et al., 2006). Thirdly,
it offers the possibility of detecting, by means of self-
reports and interviews, participants with a high
probability of developing disorders on the schizophrenic
spectrum, in the so-called psychometric high-risk
paradigm (Lenzenweger, 1994).
Studies on assessment of schizotypal personality fall
basically within the framework of psychometric high-risk
research. Their purpose is none other than to detect, by
means of psychometric tests, those subjects likely to
develop disorders on the schizophrenic spectrum, such as
schizophrenia, schizoaffective disorders or schizoid,
paranoid or schizotypal personality. Thus, high scores in
the schizotypy measure appear to indicate a certain
proneness to the development of disorders on the
schizophrenic spectrum (Chapman, Chapman, Raulin, &
Eckblad, 1994; Gooding, Kathleen, & Matts, 2005;
Kwapil, Miller, Zinser, Chapman, & Chapman, 1997),
and also constitute the best predictor with respect to
subsequent development of this type of disorder among a
broad range of psychopathological variables (Gooding et
al., 2005). With the aim of measuring the schizotypy
concept, a wide variety of self-report instruments have
been created, the most notable of which are the
Schizotypal Personality Questionnaire
, in both its long
and its short versions (Raine, 1991; Raine & Benishay,
1995), and the scales designed by the Wisconsin-
Madison University group:
Perceptual Aberration Scale
(Chapman, Chapman, & Raulin, 1978),
Magical Ideation
Scale
(Eckblad & Chapman, 1983),
Physical and Social
Anhedonia Scales
(Chapman, Chapman, & Raulin,
1976) and
Revised Social Anhedonia Scale
(Eckblad,
Chapman, Chapman, & Mishlove, 1982). The majority of
these scales have been adapted and translated for
Spanish samples by different research groups (Mata,
Mataix-Cols, & Peralta, 2005; Muntaner, García-Sevilla,
Fernández, & Torrubia, 1988).
As in the case of schizophrenia, a multidimensional
structure has been proposed for schizotypy. There has
been extensive debate in recent years on the structure of
schizotypy, with attempts to determine the nature and
number of psychopathological dimensions. The objective
of the present work is to study the nature and structure of
schizotypy through the different factorial studies carried
out on assessment self-reports. The purpose is to provide
an up-to-date picture of schizotypy and to clarify its
structure, in terms of number and content of factors, with
a view to understanding, defining and working with this
construct.
MULTIDIMENSIONALITY OF SCHIZOTYPY
Research on the dimensionality of schizotypy is closely
linked to the technique of factor analysis and the notion of
factor itself. Therefore, before embarking on the study of
the schizotypy dimensions it is necessary to clarify the
objective of factor analysis and what we understand by
factor. According to the main proponent of this technique
in Spain, Mariano Yela: “
The aim of factor analysis is to
reveal the dimensions of common variability in a given
field of phenomena. Each dimension of common
variability is called a factor
” (Yela, 1997, p. 25).
Concentrating on the factor analyses of schizophrenia
and schizotypy, the accumulated empirical evidence
indicates that schizophrenia is a multifactorial construct
(John, Khanna, Thennarasu, & Reddy, 2003; Lemos
Giráldez et al., 2006; Lindenmayer et al., 2004). The
factors found in schizotypy emerge as phenotypically
parallel to those found in schizophrenia. This similarity
between the two entities may indicate a common
aetiological mechanism (Meehl, 1962), though not
necessarily so (Venables & Rector, 2000).
Table 1 shows the factor analyses carried out in the last
decade and the number of factors, type of sample,
instrument used and type of statistical analysis. It is
important to mention that the factorial studies carried out
differ clearly in sample type (clinical, non-clinical, culture
of origin and age), number of participants, quantity and
type of measurement instruments employed and
methodological analyses, which makes their comparison
extremely difficult (Álvarez López & Andrés Pueyo, 2006;
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TABLE 1
PRINCIPAL RESEARCHERS FOR FACTORIAL
STUDIES ON SCHIZOTYPY, 1997-2007
Reference Nº of factors Scales Sample Type and nationality Type of analysis
N; Mean (SD)
Chen, Hsiao, & Lin, 1997 3 Cognitive-Perceptual SPQ PAS (1) 345; 42.9 (12.8) (1) Adults CFA
Interpersonal (2) 115; 14.0 (0.8) (2) Adolescents from Taiwan
Disorganization
Wolfradt & Straube, 1998 3 Magical Ideation/Perceptual STA 1362; 15.6 (1.12) German adolescent students EFA
Experiences
Ideas of reference/social anxiety
Suspicion
DiDuca et al., 1999 5 Cognitive JSS (MSTQ) 492; 15.5 (1.75) English adolescent students EFA-T
Perceptual
Social Anhedonia
Impulsiveness-Nonconformity
Physical Anhedonia
Martínez-Suárez et al., 1999 3 Positive MSTQ (JSS) 721; 15.8 Spanish high-school students EFA-T
Negative
Impulsive Nonconformity
Reynolds et al., 2000 3 Cognitive-Perceptual SPQ 1201;23.3 (1.17) Mauritanians CFA
Interpersonal Deficits
Disorganization
Venables et al., 2000 3 Positive (disorganized) SS 330; 20.41 (5.89) English student CFA
Negative
Social Deficit
Axelrod et al., 2001 3 Interpersonal SPQ-B 237; 15.8 (1.4) Adolescent psychiatric patients EFA
Cognitive-Perceptual
Disorganization
Rawlings et al., 2001 5 Magical Thinking STA 1073; 39.9 (16.8) English adults EFA-T
Paranoid Suspicion and Isolation
Unusual Perceptual Experiences
Social Anxiety
Suhr et al., 2001 3 Positive SPQ MAS MIS 1336 US university students EFA
Negative
Disorganized
Suhr et al., 2001 (2) 3 Positive SPQ MAS MIS 348 US university students with EFA
Negative high schizotypy
Disorganized
Paranoid Thinking
Rossi & Daneluzzo, 2002 3 Cognitive-Perceptual SPQ 347 Schizophrenics, bipolars, CFA
Interpersonal Deficits 5 subsamples OCD, depressives and control
Disorganization group, Italians M= between 25.4 and 43.4
Fossati et al., 2003 3 Cognitive-Perceptual SPQ (1) 803; 21.93 (1.57) (1) University students EFA
Interpersonal Deficits (2) 929; 16.43 (1.45) (2) Italian adolescent students
Disorganization
Stefanis et al., 2004 4 Cognitive-Perceptual SPQ 1335; 20.3 (1.8) Greek reserve soldiers CFA
Negative
Paranoid
Disorganization
Calkins et al., 2004 3 Cognitive-Perceptual SPQ (1) 135; 46.5 (15.3) (1) Relatives of psychotics EFA
Interpersonal Deficits (2) 112; 34.6 (13.3) (2) US adults
Disorganization
Linscott & Knight, 2004 4 Aberrant Beliefs TPSQ 216; 20.2 (3.8) New Zealand university EFA-T
Social Fear and Paranoia students
Anhedonia (physical and social)
Aberrant Information Processing
EDUARDO FONSECA-PEDRERO, JOSÉ MUÑIZ, SERAFÍN LEMOS-GIRÁLDEZ, EDUARDO
GARCÍA-CUETO, ÁNGELA CAMPILLO-ÁLVAREZ AND ÚRSULA VILLAZÓN GARCÍA
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Stefanis, Smyrnis, Avramopoulos, Evdokimidis,
Ntzoufras, & Stefanis, 2004).
As occurs in the case of schizophrenia, there seems to be
no agreement on the number of dimensions. Factorial
studies do not yet present a unitary picture with respect to
the structure underlying schizotypy. The numbers
proposed are two (Aycicegi, Dinn, & Harris, 2005), three
(Compton, Chien, & Bollini, 2007; van Kampen, 2006;
TABLE 1
PRINCIPAL RESEARCHERS FOR FACTORIAL
STUDIES ON SCHIZOTYPY, 1997-2007
Reference Nº of factors Scales Sample Type and nationality Type of analysis
N; Mean (SD)
Cyhlarova et al., 2005 3 Unusual Perceptual Experiences STA (children) 317; 13.3 (1.2) English adolescent students EFA
Paranoid Ideation/Social Anxiety
Magical Thinking
Lewandowski et al., 2006 3 Positive Schizotypy PAS MIS 1258;19.4 (3.7) US university students CFA
Negative Schizotypy PhARSoA
Negative affect BDI BAI
Aycicegi et al., 2005 2 Positive SPQ-B (1) 190; 20.3 (1.8) (1) Turkish university students EFA
Negative (2) 260; 18.7 (1.2) (2) US university students
Mata et al., 2005 3 Interpersonal SPQ-B 477; 21.1/20.2 (4.6/4.3) Spanish university students EFA-T
Disorganization
Cognitive-Perceptual
Badcock et al., 2006 3 Cognitive-Perceptual SPQ 352; 39.9 (10.9) Australian adults CFA
Interpersonal Deficits
Disorganization
van Kampen, 2006 3 Positive Schizotypy SSQ 771; 36.1 (10.3) Dutch adultos EFA
Negative Schizotypy
Asocial Schizotypy
Wuthrich et al., 2006 (1) 3 Cognitive-Perceptual SPQ 558; 22.7 (6.4) Australian university students CFA
Interpersonal
Disorganization
Wuthrich et al., 2006 (2) 3 Cognitive-Perceptual MIS PAS RoSA SPQ 277; 21.7(5.3) Australian university students CFA
Interpersonal
Disorganization
Mass et al., 2007 6 Negative/Interpersonal ESI,PAS, 159; 26.3 (5) German secondary and EFA-O
Positive Cognitive-Perceptual SPQ,STA university students
Disorganized Schizotypy and SPI
Magical Thinking
Social Anxiety
Psychotic Experiences
Fonseca-Pedrero et al., 2007 4 Aberrant Information Processing TPSQ 321; 13.8 (1.3) Spanish adolescents EFA-T
Social Paranoia
Anhedonia
Aberrant Beliefs
Compton et al., 2007 3 Cognitive-perceptual SPQ-B 118; 46.2 (12.2) US normal first-order relatives CFA
Interpersonal
Disorganization
Note: JSS:
Junior Schizotypy Scales
; CSTQ:
Combined Schizotypal Traits Questionnaire
; MIS:
Magical Ideation Scale
; PAS:
Perceptual Aberration Scale
; MSTQ:
Multidimensional Schizotypal Traits Questionnaire
; PAS:
Perceptual Aberration Scale
; PhA:
Physical Anhedonia
; RSoA:
Revised Social Anhedonia
; SPQ:
Schizotypal
Personality Questionnaire
; SPQ-B:
Schizotypal Personality Questionnaire Brief
; SS:
Schizotypal Scale
; STA:
Schizotypal Personality Scale
; STB:
Borderline Personality
Scale
; SSQ:
Schizotypal Syndrome Questionnaire
; BDI:
Beck Depression Inventory
; BAI:
Beck Anxiety Inventory
; O-LIFE:
Oxford-Liverpool Inventory of Feelings
. TPSQ:
Thinking and Perceptual Style Questionnaire
; ESI:
Eppenford Schizophrenia Inventory
; SPI:
Schizotypal Personality Inventory.
CFA: Confirmatory Factor Analysis; EFA-T: Orthogonal Exploratory Factor Analysis; EFA- O: Oblique Exploratory Factor Analysis.
MULTIDIMENSIONALITY OF SCHIZOTYPY
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EDUARDO FONSECA-PEDRERO, JOSÉ MUÑIZ, SERAFÍN LEMOS-GIRÁLDEZ, EDUARDO
GARCÍA-CUETO, ÁNGELA CAMPILLO-ÁLVAREZ AND ÚRSULA VILLAZÓN GARCÍA
Wuthrich & Bates, 2006) four (Mason & Claridge, 2006;
Rawlings, Claridge, & Freeman, 2001; Stefanis et al.,
2004), five (DiDuca & Joseph, 1999), or even six (Mass
et al., 2007) dimensions. These factors vary according to
participants’ sex and age (Mata et al., 2005).
The majority of studies present a three- or four-
dimensional solution in which the positive (Cognitive-
Perceptual or Unusual Perceptual Experiences) and
negative (Anhedonia, Introverted Anhedonia or
Interpersonal Deficits) dimensions of schizotypy have
been widely replicated. The current debate focuses on the
inconsistent nature of the third dimension (Suhr &
Spitznagel, 2001). In the three-dimensional models some
authors propose a (Cognitive) Disorganization dimension
(Fossati, Raine, Carretta, Leonardi, & Maffei, 2003),
while others prefer an Impulsive/Asocial Nonconformity
dimension (DiDuca & Joseph, 1999; Martínez-Suárez,
Ferrando, Lemos, Inda Caro, Paino-Piñeiro, & López-
Rodrigo, 1999; van Kampen, 2006). In the case of the
four-dimensional models the factors proposed are Positive
(Unusual Experiences), Negative (Introverted Anhedonia),
Cognitive Disorganization, and Impulsive (Mason &
Claridge, 2006) or Paranoid (Stefanis et al., 2004; Suhr
& Spitznagel, 2001) Nonconformity. The Paranoid factor
is usually combined with a Social Anxiety factor
(Cyhlarova & Claridge, 2005; Wolfradt & Straube,
1998). The Positive dimension breaks up, resulting in the
emergence of a factor of Magical Thinking or Aberrant
Thoughts (Cyhlarova & Claridge, 2005; Fonseca-
Pedrero, Campillo-Álvarez, Muñiz, Lemos Giráldez, &
García-Cueto, 2007; Linscott & Knight, 2004; Rawlings et
al., 2001). The variety of the factors found depends to a
large extent on the instrument employed for measuring
the construct. The body of research currently available
includes studies that have used in a combined way
various types of self-reports for measuring schizotypal
features; the three-dimensional solution (positive, negative
and disorganization), with or without modifications, has
emerged as the most appropriate and stable (Chen,
Hsiao, & Lin, 1997; Suhr & Spitznagel, 2001; Wuthrich
& Bates, 2006).
The Positive dimension of schizotypy, also known as
Unusual/Anomalous Perceptual Experiences or
Cognitive-Perceptual, refers to an excessive or distorted
functioning of a normal process. Its facets include
hallucinations, paranoid ideation, ideas of reference and
thinking disorders. On the other hand, the Negative
factor, also known as Anhedonia, Introverted Anhedonia
or Interpersonal Deficits, refers to a reduction or deficit in
the person’s normal behaviour. It embraces facets
involving difficulties for experiencing pleasure at a
physical and social level (anhedonia), flattened affect,
absence of close confidants and difficulties in
interpersonal relations. The Positive dimension is
associated with temporolimbic dysfunctions,
impulsiveness, antisocial behaviour (Dinn, Harris,
Aycicegi, Greene, & Andover, 2002) and symptoms of
anxiety and depression, indicating higher risk of
presenting affective problems and non-affective psychotic
disorders (Lewandowski, Barrantes-Vidal, Nelson-Gray,
Clancy, Kepley, & Kwapil, 2006). The Negative
dimension is associated with a deficit in frontal functions,
social anxiety and obsessive-compulsive phenomena
(Dinn et al., 2002). It appears to indicate a more specific
risk of disorders in the schizophrenic spectrum
(Lewandowski et al., 2006). Both the Positive and
Negative dimensions of schizotypy have been associated
with genetic vulnerability to schizophrenia (Calkins,
Curtis, Grove, & Iacono, 2004; Vollema, Sitskoorn,
Appels, & Kahn, 2002). The Disorganization factor
describes thinking problems, strange or unusual language
and strange behaviour. The Impulsive Nonconformity
factor refers to aspects related to rebelliousness,
impulsiveness and extravagance.
As Table 1 shows, with regard to type of sample in
research on schizotypy, there are studies in children and
adolescents (Cyhlarova & Claridge, 2005) and in adults
(Badcock & Dragovic, 2006). Participants tend to be
secondary-school pupils (Fonseca-Pedrero et al., 2007)
or university students (Lewandowski et al., 2006), though
there are also representative studies with reserve soldiers
(Stefanis et al., 2004), in first-order relatives of
schizophrenia patients (Calkins et al., 2004; Compton et
al., 2007) and in other types of psychiatric population
(Axelrod, Grilo, Sanislow, & McGlashan, 2001; Vollema
& Hoijtink, 2000). Sample sizes vary considerably, from
those with rather small numbers (Mass et al., 2007) to
larger-scale ones (Suhr & Spitznagel, 2001).
The most widely-used psychometric measure in factorial
studies is the
Schizotypal Personality Questionnaire
(SPQ), in its two versions (Raine, 1991; Raine &
Benishay, 1995). The SPQ has been used in different
populations with a range of different characteristics, as
well as in conjunction with other schizotypy assessment
measures and with other statistical models. As Vollema
and Hoijtink (2000) point out, the SPQ data appear to
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MULTIDIMENSIONALITY OF SCHIZOTYPY
indicate a certain convergence towards a tripartite
structure of schizotypy, invariant across sex, age
(Badcock & Dragovic, 2006; Fossati et al., 2003), culture
(nationality), religious affiliation, family conditions (e.g.,
adversity or its absence), psychopathology (Reynolds,
Raine, Mellingen, Venables, & Mednick, 2000), sample
composition and statistical models (Vollema & Hoijtink,
2000).
The last ten years have seen a tendency among
researchers to carry out both exploratory and
confirmatory factor analyses, which show a clear
equivalence. Of all the factorial studies reviewed, there is
only one approach from Rasch’s multidimensional model
(Vollema & Hoijtink, 2000), even though there are others
with different purposes (Graves & Weinstein, 2004).
Nevertheless, studies have also been carried out using
cluster analysis (Barrantes-Vidal, Fañanás, Rosa,
Caparrós, Riba, & Obiols, 2003).
As regards the nationality of participants in factorial
studies on schizotypy, the review carried out indicates the
presence of a wide variety of cultures. There are studies
with Spanish (Fonseca-Pedrero et al., 2007), Australian
(Wuthrich & Bates, 2006), American (Lewandowski et al.,
2006), Italian (Fossati et al., 2003), German (Wolfradt &
Straube, 1998), Oriental (Chen et al., 1997), Greek
(Stefanis et al., 2004), New Zealander (Linscott & Knight,
2004) and British (Rawlings et al., 2001) participants.
The structure of schizotypal features across different
nationalities indicates substantial cultural invariance,
which lends greater support to the cross-cultural validity
of the construct.
Finally, as mentioned above, the schizotypal dimensions
vary according to participants’ sex and age. As far as sex
is concerned, women score higher than men in the so-
called positive symptoms (Cyhlarova & Claridge, 2005;
Mason & Claridge, 2006; Mass et al., 2007; Mata et al.,
2005; Rawlings et al., 2001; Venables & Bailes, 1994),
as well as presenting higher total scores in some self-
reports (Claridge et al., 1996; Rawlings et al., 2001) and
Social Anxiety (Badcock & Dragovic, 2006; Fossati et al.,
2003; Mass et al., 2007). In contrast, men tend to score
higher than women in the so-called Negative dimension
of schizotypy (Claridge et al., 1996; Linscott & Knight,
2004; Mason & Claridge, 2006; Venables & Bailes,
1994; Wuthrich & Bates, 2006) and on the SPQ
subscales of flattened affect, strange behaviour and lack
of close friends (Badcock & Dragovic, 2006; Wuthrich &
Bates, 2006). With regard to age, the factorial studies
carried out in adults indicate that the Negative factor
(e.g., Introverted Anhedonia) is positively correlated with
age, whilst the Positive factor is negatively correlated with
it (Mason & Claridge, 2006; Mata et al., 2005; Rawlings
et al., 2001). In comparisons of participants according to
age, young people tend to score higher on the schizotypy
scales and/or dimensions than those who are older (Chen
et al., 1997; Fossati et al., 2003; Venables & Bailes,
1994). Factorial studies in adolescents indicate a certain
tendency towards the paranoid ideation or thinking
dimension (Cyhlarova & Claridge, 2005; Rawlings &
MacFarlane, 1994; Suhr & Spitznagel, 2001; Venables
& Bailes, 1994), though it should be borne in mind that
schizotypal dimensions in this age group may form part
of the processes of development and maturation (DiDuca
& Joseph, 1999).
RECAPITULATION
The study of personality dimensions is a classic field but a
highly pertinent one within psychology. In research on
schizotypy there have so far been very few theoretical
reviews attempting to provide a comprehensive account
of the large number of studies on the subject. The aim of
the present work is to explore the principal factor analyses
of schizotypy. The purpose is none other than to analyze
the structure and nature of schizotypy, in terms of the
number and content of factors, with a view to better
definition and understanding of the construct and
consideration of its parallels with schizophrenic
psychosis. The importance of schizotypy resides in the
detection of people vulnerable to the development of
disorders on the schizophrenic spectrum, in the study of
symptoms similar to schizophrenia without side effects of
the medication, and in an improved understanding of the
mechanisms underlying schizophrenia and the links
between the two entities.
The review of factor analyses reveals that schizotypy is a
multidimensional construct based on three or four factors
phenotypically similar to those found in schizophrenia.
The Positive (Unusual Experiences) and the Negative
(Anhedonia) dimensions appear in a consistent fashion
throughout the literature. The third (or even fourth)
dimension emerges as a factor of Disorganization, of
Impulsive (Asocial) or Paranoid Nonconformity
(sometimes linked to a Social Anxiety factor). In some
studies the Positive factor of schizotypy breaks off,
constituting a single factor called Magical Thinking or
Aberrant Beliefs. The relationships between the factors
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EDUARDO FONSECA-PEDRERO, JOSÉ MUÑIZ, SERAFÍN LEMOS-GIRÁLDEZ, EDUARDO
GARCÍA-CUETO, ÁNGELA CAMPILLO-ÁLVAREZ AND ÚRSULA VILLAZÓN GARCÍA
found are multiple, varied and confused, similar terms
sometimes being used to define different dimensions. The
variety of studies carried out over the last ten years
reveals the richness of this field, in which there would
seem to emerge a certain coherence in the nature and
structure of schizotypy, even though it is still not a fully
unitary concept. The main limitation found on making
comparisons between factorial studies concerns the type
and quantity of instruments, the nature of the sample, and
the statistical model employed.
The
Schizotypal Personality Questionnaire
(SPQ), in
both its long and its short versions, is the most widely used
instrument for the assessment of schizotypy in the factorial
studies reviewed. The samples used are basically made
up of university students, among whom the schizotypy
dimensions behave differently according to sex and age.
As is also the case for schizophrenia, women tend to
score higher than men in the Positive dimension, whilst
men score higher in the Negative dimension.
The possible limitations observed in the review can be
found at the methodological level. First of all, there are
very few studies using samples selected at random from
the population. Secondly, the majority of research
concentrates on the normal population, on university
students from introductory Psychology courses. Thirdly,
there is scarce use of other, more recent models or
statistical techniques, such as Item Response Theory (IRT).
And fifthly, and as pointed out above, the features of
schizotypal personality vary in accordance with certain
characteristics of participants, with few studies evaluating
systematically the differential functioning of the items
(Guilera, Gómez, & Hidalgo, 2006).
Schizotypy has generated its own research line as
regards its structure, nature and relationships with other
constructs. Studies on schizotypy can be categorized
according to three periods. The first of these saw the
creation of scales for evaluating features similar to those
of schizophrenia, such as the Wisconsin-Madison
University group scales, referred to earlier. Subsequently,
schizotypy measurement scales were designed from a
multidimensional and comprehensive perspective of
psychosis proneness, as is the case of the
Oxford-
Liverpool Inventory of Feeling and Experiences
(O-LIFE)
(Mason, Claridge, & Jackson, 1995). In a third period,
the current one, researchers are carrying out factor
analyses of a confirmatory type, as well as factor analyses
employing in a combined fashion different self-reports for
assessing the schizotypy dimensions. Work is also being
done using factor analyses in conjunction with other
scales that measure constructs related to schizotypal
features, such as dissociative experiences (Pope &
Kwapil, 2000), obsessive-compulsive disorder (Suhr,
Spitznagel, & Gunstad, 2006), Asperger’s syndrome
(Hurst, Nelson-Gray, Mitchell, & Kwapil, 2006) or
anxious-depressive symptomatology (Lewandowski et al.,
2006).
Future research in the field of schizotypy should take into
account such methodological limitations. The relationship
between schizotypy and other psychopathological
constructs (such as obsessive-compulsive disorder) is
interesting with regard to both clinical practice and
comorbidity studies. The development of combined
factorial studies employing different types of schizotypy
assessment instruments also appears to make sense with a
view to unification of the construct. Globalization and
internationalization lead to an increase in the number of
test adaptations and translations from one culture to
another, and such adaptations and translations should be
carried out with rigour, following the guidelines of the
International Test Commission
(Muñiz & Hambleton,
1996). Studies comparing schizotypy across cultures are
of great relevance to improved understanding of the
cross-cultural, universal nature of schizotypy. Finally,
instruments for evaluating schizotypy should demonstrate
their predictive value, sensitivity and specificity in
independent studies with a view to early detection and
intervention in those who are prone to the development of
disorders on the schizophrenic spectrum.
ACKNOWLEDGEMENTS
This research was financed by the Spanish Ministry of
Education and Science (BES-2006-12797, SEJ 2005-
08924, SEJ-2005-08357), and by the Education Board
of the Principality of Asturias (IB-05-02, COF05-005).
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